五个关于饮水的神话Five Myths About Drinking Water
原文地址：Five Myths About Drinking Water
译文地址：五个关于饮水的神话
翻译：竹刃
瓶装水对你而言，真的就比自来水好吗？或者你该选择正在冒泡的维他命水？专家则说，别理它们。这些产品没有一样对你的健康有益。下面，我们来看看五个有关饮水获益的神话。
不过首先，你怎样才知道是否饮用了足量的水，专家又说，这很简单。如果你不感到口渴，就说明你摄入了足够的水分。
神话1每天喝八杯水
专家说，每天大量地摄入水分最健康并没有显著的帮助，那哪来的喝八杯水的标准呢？来自宾州大学的肾脏专家Stanley Goldfarb说：“谁知道呢？”
神话2 喝大量的水能去除体内毒素
肾脏从我们的血液系统中过滤掉毒素，然后通过尿液排出。问题是，大量的喝水能提高我们肾脏的效率吗？
Goldfarb说，不，事实上，大量的饮水将降低肾脏的过滤功能。这是一个微妙的问题。
神话3 大量的水分等于健康的皮肤
我们的身体大约由60%的水分组成，所以以一个200磅的成人而言，他的身体中大约有120磅水。
每天多喝些水似乎只有很小的功效。“这只是很小的一部分，对于整个身体而言是微不足道的”Goldfarb又说道，他的最新论文发表在美国的泌尿科学期刊上。
2007年，一项关于饮水的美容功效研究结果表示，饮用500毫升的水，就可以增加皮肤的血液循环能力。但Goldfarb说，这些作用在临床上并不清楚。
神话4 大量饮水有助于减肥
也许一种更准确的解释是：饮水是节食的有效手段。
来自匹兹堡大学的Madeline Fernstrom说，水不含卡路里，所以对减肥者而言是极好的节食方式。因而你可以始终让你的嘴巴不停地运动，却不摄入任何热量，而同时由获得了饱食感。
但水并没有那么神奇，她补充道。其他的零卡路里选择，诸如苏打水，也许同样不错。
神话5 在锻炼中很容易脱水
当一个人失去2%的水会导致脱水。对于一个200磅的人而言，也就是失去4磅水。
马拉松选手，自行车运动员以及徒步者都有必要知道如何辨别脱水症状。“在干燥炎热的天气下，增加水分的摄入尤其明显。”Goldfarb说道。
美国体育卫生学院建议运动员在运动前两个小时补充16盎司的水分。
但是如果你仅仅在公园中漫步，水壶并不是很有必要。Goldfarb建议道，当你口渴的时候再喝水！
Original: Five Myths About Drinking Water
Translated version: Five Myths About Drinking Water
Translated by: 竹刃
Is bottled water really any better for you than tap water? Or should you go for the vitamin water fizzing away over there? The experts say: ignore them. Not one of these products does your health any good. Below, let’s look at five myths about the benefits of drinking water.
But first, how do you know whether you’ve drunk enough water? Again the experts say it’s simple: if you don’t feel thirsty, you’ve taken in enough.
Myth 1: Drink eight glasses of water a day
Experts say there is no real evidence that taking in large amounts of water every day is healthiest. Then where does the eight-glasses standard come from? “Who knows?” says Stanley Goldfarb, a kidney expert at the University of Pennsylvania.
Myth 2: Drinking lots of water flushes toxins from the body
The kidneys filter toxins out of our bloodstream, which then leave through the urine. The question is: does drinking lots of water improve our kidneys’ efficiency?
No, says Goldfarb. In fact, heavy water intake reduces the kidneys’ filtering function. It’s a subtle matter.
Myth 3: Plenty of water equals healthy skin
Our bodies are roughly 60% water, so for a 200-pound adult, that’s about 120 pounds of water in the body.
Drinking a bit more water each day seems to have only a tiny effect. “It’s such a small fraction, trivial for the body as a whole,” adds Goldfarb, whose latest paper appeared in an American urology journal.
In 2007, a study on the cosmetic benefits of drinking water reported that drinking 500 milliliters of water can boost blood circulation in the skin. But Goldfarb says the clinical meaning of these effects is unclear.
Myth 4: Drinking lots of water helps with weight loss
Perhaps a more accurate way to put it: drinking water is an effective tool for dieting.
Water has no calories, says Madeline Fernstrom of the University of Pittsburgh, which makes it a superb dieting device for anyone losing weight: you can keep your mouth constantly busy without taking in any calories, and get the feeling of being full at the same time.
But water isn’t that magical, she adds. Other zero-calorie choices, such as soda water, may be just as good.
Myth 5: It’s easy to get dehydrated during exercise
Dehydration sets in when a person loses 2% of their water. For a 200-pound person, that means losing 4 pounds of it.
Marathoners, cyclists, and hikers all need to know how to recognize the signs of dehydration. “In hot, dry weather the increased need for water is especially clear,” says Goldfarb.
The American College of Sports Medicine recommends that athletes drink 16 ounces of water two hours before exercise.
But if you’re just strolling in the park, the water bottle isn’t really necessary. Goldfarb’s advice: drink when you’re thirsty!
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